Matrix band

ABSTRACT

The invention relates to a matrix band that is characterized in that it comprises fibers and a matrix, at least a portion of said matrix being at least partially uncured. The invention further relates to a dental restoration kit, a prepreg and the use of said matrix.

FIELD OF THE INVENTION

This invention relates to a dental matrix band. The invention furtherrelates to a dental restoration kit, a prepreg as well as to the use ofthe present matrix band.

BACKGROUND OF THE INVENTION

The publications and other materials used herein to illuminate thebackground of the invention, and in particular, the cases to provideadditional details respecting the practice, are incorporated byreference.

It is common dental practice to use metal or polymer matrix band infabrication of dental restorations, such as fillings of compositeresins. The matrix band gives support for the non-polymerizedrestorative composite resin before it is polymerized. Another meaning ofthe matrix band is to help the dentist to form the filling to thedesired form, i.e. giving for instance good approximal contacts to theadjacent teeth. The dentist has used various types of matrix bands formany decades in the tooth filling process. Matrix bands have beendescribed in the patent literature e.g. in U.S. Pat. No. 1,255,109, U.S.Pat. No. 2,310,448, U.S. Pat. No. 2,594,367 and U.S. Pat. No. 5,380,198.The matrix band is also referred to as matrix strip in the literature.

The problem related to the state-of-the-art matrix bands relates to theremoval of the matrix bands after the composite resin has beenpolymerized. The removal causes a gap between the filling and adjacenttooth. For example, typical thickness for a dental matrix band made ofMylar® (a polyester) film is 0.05 mm.

The matrix band should also be transparent in order facilitate thephotopolymerization of the restorative composite resin through thematrix band. Metallic matrix bands do not facilitate photopolymerizationthrough the matrix band.

One additional problem related to the dental fillings is recurrent cuspfractures besides the filling although the composite resin shouldsupport the cusps and reinforce the tooth by good adhesion of thecomposite resin restoration to the tooth.

OBJECTS AND SUMMARY OF THE INVENTION

The object of this invention is to provide a matrix band that solves theabove-mentioned problems. It is especially an object of the presentinvention to provide a matrix band that allows to minimize or tocompletely avoid the formation of a gap between the filling formed andthe adjacent tooth.

A further object of this invention is to provide a matrix band thatminimizes the cusp fractures besides the filling formed.

The above-mentioned problems are solved by the matrix band according tothe present invention. A typical matrix band according to the inventionis characterized in that it comprises fibers and a matrix, at least aportion of said matrix being at least partially uncured.

The present invention also relates to a dental restoration kitcomprising a matrix band according to the present invention, arestorative dental composite and an adhesive.

The invention further relates to a prepreg for use as a matrix band aswell as to the use of the present matrix band for the manufacturing of adental restoration, a dental bridge or a dental crown and in dental andmedical applications.

A typical prepreg according to the invention comprises fibers and amatrix, at least a portion of said matrix being at least partiallyuncured.

DETAILED DESCRIPTION OF THE INVENTION

The invention is disclosed in the appended independent claims. Thedependent claims define various embodiments of the invention.

A typical matrix band according to the present invention ischaracterized in that it comprises fibers and a matrix, at least aportion of said matrix being at least partially uncured.

In this application, by curing it is meant polymerization and/orcrosslinking. By matrix, it is understood the continuous phase of thecomposition and by uncured matrix it is meant a matrix that is in itsdeformable state but that can be cured, i.e. hardened, to anon-deformable state. The uncured matrix may already comprise some longchains but it is essentially not yet polymerized and/or crosslinked. Bypartially uncured it is meant that the material is partly cured butstill contains short chains that can be polymerized and/or crosslinked,and that the material is still in a deformable state. By prepreg, it ismeant a semi-manufactured product, that is, a product that is no or onlypartly polymerized yet still deformable. The polymerization of a prepregleads to a composite. The words “composite” and “cured prepreg” may beused interchangeably. “Dental restoration” is used as meaning typicaldental fillings but also as a general term to include all dentalrepairs, such as crowns and bridges.

The matrix band according to the present invention thus comprises bothfibers and a matrix. By the matrix, it is meant the resin materialbetween and optionally on the fibers that wets the fibers. Some examplesof suitable fibers and materials for the matrix are given below. Atleast a portion of said matrix is at least partially uncured, i.e. atleast a portion of it can be further polymerized and/or crosslinked.Furthermore, said at least a portion of said matrix is capable ofchemical and/or mechanical bonding, i.e. it can be polymerized and/orcrosslinked, as said above, but it can also form mechanical bonding,such as interlocking or a structure known as interpenetrating networks.It may also be porous and thus capable of mechanical bonding.

Fiber-reinforced composite technology has been introduced to dentistryduring late 1990's mainly for reinforcing dentures against cracks and tomake fiber-reinforced composite fixed partial dentures. Its use in thepresent application, i.e. a matrix band, has however not been suggestedearlier.

This invention thus consists of a combination of fiber-reinforcedcomposite technologies to form a dental matrix band. With the presentinvention it is possible to provide a new approach to make tooth fillingand at same time to reinforce the tooth structure to prevent the cuspfractures, or to stabilize tooth with existing minor fractures. Furtheradvantages can also be achieved e.g. the prevention of marginal leakagebetween the filling and the tooth, when the fiber-reinforced compositeis covering the border area between the filling and tooth.

The intention of the matrix band according to the present invention isto be attached to the filling composite resin and to form an integralpart of the tooth-filling system after the filling composite resin hasbeen cured. Thus, the matrix band is not removed after making thefilling. The invention further benefits the tooth-filling system byoffering protection for cusps against fractures by encapsulating thecusps with the matrix band and to minimize the microleakage by coveringthe border region of the filling and tooth. The matrix band can also beused to encapsulate old restorations and dental bridges. It is alsoespecially suitable to be used to encapsulate frameworks offiber-reinforced composite bridges to the abutment teeth.

The matrix band according to the present invention is preferably used onan untreated tooth, i.e. on tooth that has not been drilled. The surfaceof the tooth may have been previously etched or a priming may have beenapplied. These treatments are common in the art of dentistry and wellknown to persons skilled in the art.

The present invention thus solves the problems mentioned above, i.e. itprovides a matrix band that allows to minimize or to completely avoidthe formation of a gap between the filling formed and the adjacenttooth. Furthermore, it provides a matrix band that minimizes the cuspfractures besides the filling formed. The matrix band according to thepresent invention also provides for more surface of attachment for thedental restoration.

The matrix band according to the present invention is made offiber-reinforced prepreg materials, for example such as those describedin patent U.S. Pat. No. 6,197,410 (herein incorporated by reference).According to an embodiment of the invention, the matrix band is made ofwoven glass fibers wetted with a highly viscous resin. It also possiblethat all of the resin matrix of the fiber-reinforced composite matrixband is at least partially in its non-cured form when the matrix band isplaced on tooth. According to an embodiment, it is also possible to havethe matrix of the matrix band to be in a cured form at one part of theband and no or partly cured form in another part of the band. In thislatter case, it is preferred to have a cured matrix part, i.e. rigidpart at margin of the band to help placing the matrix band into thegingival pocket. In the case of a cured matrix, it is preferred to havea porous polymer matrix allowing formation of interpenetrating polymernetwork bonding between the restorative composite resin and the matrixband to ensure attachment of the matrix to the composite filling. Apolymer matrix of this type has been described in patent U.S. Pat. No.6,197,410. If the matrix of the matrix band is in its non-cured formwhen the matrix is used, then once the restorative composite resin (byrestorative composite resin, it is meant the filling material of thetooth cavity) is cured, the attachment of the matrix band is based onthe polymerization and/or crosslinking by free radical polymerization ofthe monomers of the matrix of the matrix band and on the polymerizationand/or crosslinking of the monomers of the restorative composite resin,at the same time.

When the matrix band according to the present invention is used, it isplaced totally or partially around the remaining tooth being in contactwith the possible adjacent tooth. When the restorative resin is appliedto the cavity, it becomes into contact with the matrix band. During thecuring of the restorative composite resin, the matrix of the matrix bandis also cured and attached to the composite. At the same time, thematrix band covers the tooth substance underneath and encapsulates thetooth. The encapsulation by the fiber-reinforced matrix band reinforcesthe tooth-filling system against fractures of tooth. The filling ispreferably finished and polished in conventional ways and it is possibleto cover the matrix band with restorative composite resin to increasethe wear resistance of the surface of the matrix band.

When the matrix band according to the present invention is used as apart of a fiber-reinforced composite bridge, the matrix band is placedover the framework and abutment tooth to encapsulate the tooth, possiblefillings of the tooth and partially or totally the framework of thebridge. The matrix band encapsulation can be made for the bridges andrestorations made by direct technique, by indirect technique or by theircombination. The matrix band will remain as an integral part of thetooth-bridge or more generally, tooth-restoration system.

It is also possible to overlay the matrix band that has been cured witha layer of restorative composite resin to reshape the tooth morphologyto fulfill the needs of the occlusion. By this, the attached matrix bandsupports the composite resin that has been used to reshape the tooth.

The fiber or fibers used in the composition may be any fiber known perse that are compatible with the matrix used and a person skilled in theart will be able to readily assess which fiber is the most suitable forthe intended application.

The fibers may for example be selected from a group consisting of inertglass fibers (such as S or E glass), bioactive glass fibers, silicafibers, quartz fibers, ceramic fibers, carbon/graphite fibers, aramidfibers, ceramic fibers, poly(p-phenylene-2,6-benzobisoxazole) fibers(PBO),poly(2,6-diimidazo(4,5-b4′,5′-e)pyridinylene-1,4(2,5-dihydro)phenylenefibers (PIPD), polyolefin fibers, fibers prepared from copolymers ofolefins, polyester fibers, polyamide fibers, polyacrylic fibers, sol-gelprocessed silica fibers, collagen fibers, cellulose fibers and modifiedcellulose fibers. Any combination of said fibers may be used.Poly(p-phenylene-2,6-benzobisoxazole) fibers andpoly(2,6-diimidazo(4,5-b4′,5′-e)pyridinylene-1,4(2,5-dihydro)phenylenefibers belong to a group called rigid-rod polymer fibers. It is obviousto a person skilled in the art that any other known fibers may be usedin the present invention, provided it is possible to obtain a suitableadhesion between said fibers and matrix, in order to achieve the desiredmechanical properties. In dental applications the most suitable fibersare, at the moment of filing this application, glass fibers due to theirgood cosmetic and esthetic properties and because the glass fibers allowlight polymerization to be performed through the matrix band.

The fibers of the matrix band may be in any desired form, such ascontinuous fibers, chopped fibers or in the form of woven or nonwovenmat or sheet. The orientation of the fibers may be unidirectional,bidirectional, tridirectional or have a random orientation.

The matrix of the matrix band may be made of any suitable monomer orpolymer or a mixture of them.

The matrix of the matrix band may comprise monomers selected from thegroup consisting of methyl acrylate, ethyl acrylate, propyl acrylate,isopropyl acrylate, n-hexyl acrylate, styryl acrylate, allyl acrylate,methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropylmethacrylate, n-butyl methacrylate, isobutyl methacrylate, 2-ethylhexylmethacrylate, cyclohexyl methacrylate, isobornyl methacrylate,tetrahydrofurfuryl methacrylate, benzyl methacrylate, morpholinoethylmethacrylate, diurethane dimethacrylate, acetoacetoxy ethyl methacrylate(AAEM), methacrylate functionalized dendrimers, other methacrylatedhyperbranched oligomers, hydroxymethyl methacrylate, hydroxymethylacrylate, hydroxyethyl methacrylate, hydroxyethyl acrylate,hydroxypropyl methacrylate, hydroxypropyl acrylate, tetrahydrofurfurylmethacrylate, tetrahydrofurfuryl acrylate, glycidyl methacrylate,glycidyl acrylate, triethylene glycol diacrylate, tetraethylene glycoldimethacrylate, tetraethylene glycol diacrylate, trimethylolethanetrimethacrylate, trimethylolpropane trimethacrylate, pentaerythritoltrimethacrylate, trimethylolethane triacrylate, trimethylolpropanetriacrylate, pentaerythritol triacrylate, pentaerythritoltetramethacrylate, pentaerythritol tetra-acrylate, ethylenedimethacrylate, ethylene diacrylate, ethylene glycol dimethacrylate,diethylene glycol dimethacrylate, triethylene glycol dimethacrylate(TEGDMA), ethylene glycol diacrylate, diethyleneglycol diacrylate,buthylene glycol dimethacrylate, buthylene glycol diacrylate, neopentylglycol dimethacrylate, neopentyl glycol diacrylate, 1,3-butanedioldimethacrylate, 1,3-butanediol diacrylate, 1,4-butanedioldimethacrylate, 1,4-butanediol diacrylate, 1,6-hexanedioldimethacrylate, 1,6-hexanediol diacrylate,di-2-methacryloxyethyl-hexametylene dicarbamate,di-2-methacryloxyethyl-trimethylhexametylene dicarbamate,di-2-methacryloxyethyl-dimethylbenzene dicarbamate,di-2-methacryloxyethyl-dimethylcyclohexane dicarbamate,methylene-bis-2-methacryloxyethyl-4-cyclohexyl carbamate,di-1-methyl-2-methacryloxyethyl-hexamethylene dicarbamate,di-1-methyl-2-methacryloxyethyl-trimethylhexamethylene dicarbamate,di-1-methyl-2-methacryloxyethyl-dimethylbenzene dicarbamate,di-1-methyl-2-methacryloxyethyl-dimethylcyclohexane dicarbamate,methylene-bis-1-methyl-2-methacryloxyethyl-4-cyclohexyl carbamate,di-1-chloromethyl-2-methacryloxyethyl-hexamethylene dicarbamate,di-1-chloromethyl-2-methacryloxyethyl-trimethylhexamethylenedicarbamate, di-1-chloromethyl-2-methacryloxyethyl-dimethylbenzenedicarbamate, di-1-chloromethyl-2-methacryloxyethyl-dimethylcyclohexanedicarbamate, methylene-bis-2-methacryloxyethyl-4-cyclohexyl carbamate,di-1-methyl-2-methacryloxyethyl-hexamethylene dicarbamate,di-1-methyl-2-methacryloxyethyl-trimethylhexamethylene dicarbamate,di-1-methyl-2-methacryloxyethyl-dimethylbenzene dicarbamate,di-1-methyl-2-methacryloxyethyl-dimethylcyclohexane dicarbamate,methylene-bis-1-methyl-2-methacryloxyethyl-4-cyclohexyl carbamate,di-1-chloromethyl-2-methacryloxyethyl-trimethylhexamethylenedicarbamate, di-1-chloromethyl-2-methacryloxyethyl-dimethylbenzenedicarbamate, di-1-chloromethyl-2-methacryloxyethyl-dimethylcyclohexanedicarbamate,methylene-bis-1-chloromethyl-2-methacryloxyethyl-4-cyclohexyl carbamate,2,2-bis(4-(2-hydroxy-3-methacryloxy)phenyl)propane (BisGMA),2,2′-bis(4-methacryloxyphenyl)propane,2,2′-bis(4-acryloxyphenyl)propane,2,2′-bis[4(2-hydroxy-3-acryloxyphenyl)propane,2,2′-bis(4-methacryloxyethoxyphenyl)propane,2,2′-bis(4-acryloxyethoxyphenyl)-propane,2,2′-bis(4-methacryloxypropoxyphenyl)propane,2,2′-bis(4-acryloxy-propoxyphenyl)propane,2,2′-bis(4-methacryloxydiethoxyphenyl)-propane,2,2′-bis(4-acryloxydiethoxyphenyl)propane,2,2′-bis[3(4-phenoxy)-2-hydroxypropane-1-methacrylate]propane,2,2′-bis[3(4-phenoxy)-2-hydroxypropane-1-acrylate]propane and mixturesthereof.

The matrix may also be made of crosslinkable monomers or polymers suchas ε-caprolactone, polycaprolactone, polylactides, polyhydroxyproline,and other biopolymers as well as polyamides, polyurethane, polyethylene,polypropylene, other polyolefins, polyvinyl chloride, polyester,polyether, polyethyleneglycol, polysaccharide, polyacrylonitrile,poly(methyl methacrylate), phenol-formaldehyde, melamine-formaldehyde,and urea-formaldehyde. The matrix may naturally also consist of amixture of a monomer(s) and a polymer(s).

Dendrimers having 5 to 35 functional groups such as methacrylate oracrylate groups may also be used. Multifunctionality forms highlycross-linked matrix and decreases the creep of the polymer in thelong-term use. Examples of suitable dendrimers are given for example inU.S. Pat. No. 5,834,118 (incorporated herein by reference). Dendrimersmay particularly be startburst or hyperbranched methacrylatedpolyesters.

According to an embodiment of the invention, the matrix is selected fromthe group consisting of methyl methacrylate, hydroxyethyl methacrylate,urethan dimethacrylate, triethylene glycol dimethacrylate,2,2-bis(4-(2-hydroxy-3-methacryloxy)phenyl)propane, polymethylmethacrylate, starburst methacrylated polyesters, hyperbranchedmethacrylated polyesters and mixtures thereof.

A typical polymer in dental applications at the moment of filing thisapplication is polymethyl methacrylate (PMMA), especially PMMA having amolecular weight between 13 000 and 996 000 g/mol. More preferably themolecular weight is between 20 000 and 300 000 g/mol, such a molecularweight allowing an especially easy formation of a dense polymer matrixfor the finished composite. It is naturally also possible to usemixtures of PMMA's having different molecular weights.

The curing of the matrix band according to the present invention isperformed by a known curing process suitable for the selected matrix.The curing may be induced for example by electromagnetic radiationselected from the group consisting of visible light, ultra-violet light,blue light and laser irradiation. According to another embodiment, saidmatrix is autopolymerizable and the curing is induced by applying anactivator on the matrix band. The humidity of air or the oxygen of airmay also functions as an activator. It is also possible to use matrixesthat are stored in low temperatures (under room temperature or below 0°C.) after manufacturing and that autopolymerize once the temperature isincreased to room temperature. The preferable curing initiation isobtained by radiation with blue light or by laser with the help ofinitiators and activators for the polymerization and/or crosslinking.

The matrix band according to the present invention may further compriseparticulate filler material, such as inert glass, bioactive glass, metaloxides, ceramics, polymers and mixtures thereof Metal oxides may forexample be used as radio or X-ray opaque materials or as coloringmaterials. It is for example possible to make the matrix band such thatit is not further necessary to coat it with another material to make thefinal outer surface of the dental restoration.

The thickness and stiffness of the matrix band may be varied accordingto the intended application of said matrix. The variations are wellknown to a person skilled in the art and it is possible to affect thethickness and stiffness of the matrix band by varying the fibers, theirorientation and the nature and amount of the matrix. Typically, thethickness of the matrix band is between 0.05 and 1.5 mm. Thecross-section of a matrix band need not to be constant, it may forexample be thinner in its edges. The variations in thickness andstiffness affect the mechanical properties of the matrix band and theresulting dental restoration. These variations and their consequences onthickness and stiffness are obvious to persons skilled in the art, andthe proper choice can be ascertained by a few simple tests.

The matrix band can be made for example of a glass fiber weave having athickness of 0.06 mm that has been pre-impregnated as described inpatents U.S. Pat. No. 5,846,640 and U.S. Pat. No. 6,197,410 (hereinincorporated in reference). The matrix band is placed to cover the axialsurfaces of a tooth. The filling composite that is applied into thecavity comes into contact with the matrix band and after curing of thematrix it will be attached to the filling composite. The matrix bandremains on the axial surfaces of the tooth and will usually be coveredwith a layer of a filling composite to form a polishable and toothcolored surface on the matrix band. The matrix band behaves as a capsuleon the tooth and protects the remaining parts of tooth, such as cusps,against fractures.

The matrix band according to the present invention may be applied with aspecific tool or with fingers. An example of a tool is presented belowin connection with the drawing.

The present invention thus relates to a matrix band in the sense that itis generally understood in the art. The present inventors have howeveralso noticed that the matrix band can also be used in other applicationsthan dental restoration. These applications are more extensivelyexplained below.

The present invention also relates to a dental restoration kitcomprising a matrix band according to the present invention, arestorative dental composite and an adhesive. By restorative dentalcomposite it is meant normal tooth filling material. The adhesive isused to attach the matrix band to the tooth to be restored, although thematrix band may be sticky in itself and does not necessarily need aseparate adhesive. In general, adhesives are however used. The kit mayfurther comprise an applicator device for positioning said matrix bandinto place. The matrix band may also be pre-shaped in the form of adental restoration, a dental crown or a dental bridge, for a moreconvenient use. It is possible to pre-shape the matrix band to any formand size.

The invention further concerns a prepreg comprising fibers and a matrix,at least a portion of said matrix being at least partially uncured, foruse as a dental matrix band. The examples of suitable materials forfibers and matrix given above apply to this embodiment of the inventionalso. The prepreg according to the present invention may also be used inall the applications mentioned for the matrix band in thisspecification.

The present invention yet further relates to the use of a matrix bandaccording to the present invention for the manufacturing of a dentalrestoration, a dental bridge or a dental crown. In these uses, thematrix band forms an integral part of the finished dental restoration,dental bridge or dental crown. The matrix band according to the presentinvention may also be used as an occlusal matrix band, in order to givesupport for the occlusal surface of the tooth.

The present invention still relates to the use of a matrix bandaccording to the invention in dental applications. Said application maybe selected for example from dental restoration, dental bridge, dentalcrown, dental restorations and endodontic treatment. The matrix bandaccording to the present invention may advantageously be used in themanufacturing of a micro-invasive crown, since it allows themanufacturing of a crown without substantial drilling of the adjacentteeth.

The matrix band according to the present invention may further be usedas encapsulation material of parts of fiber-reinforced compositebridges, as temporary isolation device during endodontic treatment, as aframework for veneering composite resins of dental bridges and crowns oras a repair material for dental restorations.

Some of the above-mentioned uses are discussed more in detail inconnection with the drawing below. By temporary isolation device duringendodontic treatment, it is meant to use the matrix band according tothe present invention to prevent saliva for entering the root canal.Indeed, saliva should not enter said root canal, which is difficult toprevent in cases where the tooth is broken down to the level of thegingiva. The matrix band is temporarily positioned around the end of theroot, in order to elevate its upper end to prevent the entering ofsaliva into the root canal, during the treatment. The matrix bandaccording to the present invention may further be used in any otherdental restorations where it is desirable to increase the strength ofthe finished restoration.

The present invention further relates to a method of manufacturing adental restoration.

The method comprises the following steps:

-   -   drilling a cavity on the tooth to be repaired,    -   etching or priming the surface of said tooth,    -   applying a matrix band according to the present invention around        said tooth, and    -   filling said cavity with restorative material.

The method optionally also comprises one or more of the further stepsof:

-   -   curing the restorative material,    -   covering the thus obtained restoration with a covering material,    -   polishing the thus obtained finished restoration.

The matrix band may be cured immediately after it has been appliedaround the tooth, partly or fully, or it may be cured together with therestorative material, or the curing of the matrix band may be finishedat the same time as the restorative material is cured.

The present invention further relates to a method of manufacturing adental bridge, comprising the steps of:

-   -   preparation of teeth    -   etching or priming the surface of the abutment teeth adjacent to        the crown to be manufactured,    -   positioning a fiber framework on said abutment teeth,    -   positioning a matrix band according to the present invention on        each of said abutment teeth,    -   manufacturing of a pontic,    -   finishing the esthetic look of the pontic and the adjacent        teeth, and    -   polishing the dental bridge obtained.

The method may additionally comprise the step of covering the matrixband with a layer of filling composite resin or other suitable material.The matrix band and/or the fiber framework may be cured immediatelyafter it/they has been applied on the teeth, partly or fully, or it/theymay be cured together with the pontic. The manufacturing of a pontic ismade according to any method known in the art. The step of finishing theesthetic look of the pontic and the adjacent teeth typically includeslayering and/or covering the pontic and optionally of the adjacentteeth, for example with a composite layering technique.

The present invention further relates to a method of manufacturing amicro-invasive dental crown, comprising the steps of:

-   -   preparation of the tooth,    -   etching or priming the remaining surface of said tooth,    -   applying a matrix band according to the present invention around        said tooth,    -   manufacturing an artificial crown within said matrix band,    -   curing the material of said crown,    -   applying a layer of surface material on said cured crown, and    -   polishing the surface of the obtained finished crow.

The matrix band may be cured immediately after it has been appliedaround the tooth, partly or fully, or it may be cured together with themanufacturing of the artificial crown.

In this specification, except where the context requires otherwise, thewords “comprise”, “comprises” and “comprising” means “include”,“includes” and “including”, respectively. That is, when the invention isdescribed or defined as comprising specified features, variousembodiments of the same invention may also include additional features.Also, the reference signs should not be construed as limiting.

The invention is described below in greater detail by the following,non-limiting drawings.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 illustrates schematically the use of a matrix band according to afirst embodiment of the invention.

FIG. 2 illustrates schematically the use of a matrix band according to asecond embodiment of the invention.

FIG. 3 illustrates schematically the use of a matrix band according to athird embodiment of the invention.

FIG. 4 illustrates schematically the use of a matrix band according to afourth embodiment of the invention.

FIG. 5 illustrates schematically a device for placing a matrix bandaccording to the invention.

FIG. 6 illustrates schematically the use of a matrix band according to afifth embodiment of the invention.

FIG. 7 illustrates the enclosed Example.

DETAILED DESCRIPTION OF THE DRAWING

FIG. 1 illustrates schematically the use of a matrix band according to afirst embodiment of the invention. The drawing illustrates a premolartooth 1 having mesio-distal cavity 2 to be filled with the restorativecomposite resin (not shown). A fiber-reinforced composite matrix band 3is placed around the tooth 1 offering support for the restorativecomposite resin to be applied to the cavity 2. When the restorativecomposite resin is cured, the composite resin is bonded to the matrixband 3 that will remain as a part of tooth-filling system. Approximalcontact to the tooth 4 behind the restored premolar tooth 1 remainswithout gap formation because the matrix band 3 is not removed from thetooth 1 after curing the composite resin.

FIG. 2 illustrates schematically the use of a matrix band according to asecond embodiment of the invention. In this embodiment, a matrix band isused to reinforce a fiber composite bridge. The matrix band 5 is placedover of a tooth to encapsulate and protect the fibers of the framework6.

To protect the fibers of a continuous unidirectional fiber compositeframework 6 of a bridge on abutment teeth 7 and 8, a matrix band 5 isplaced on the fibers of the framework 6. The matrix band 5 is here shownabove the framework 6 for sake of clarity. The matrix band 5 forms,after curing, a capsule on the framework fiber—tooth system. In additionto the protection effect of the matrix band 5, the matrix band 5 alsotransfers stresses to larger surface area of the abutment teeth 7, 8 andthus reduces the debonding stresses. The matrix band 5 is preferablycovered with a layer of filling composite resin where there is room andneed for the composite material in the occlusion.

FIG. 3 illustrates schematically the use of a matrix band according to athird embodiment of the invention. More precisely, the Figureillustrates a fractured tooth repaired with a crown supported by amatrix band. Firstly, a matrix band 10 is placed on the root of apremolar 9 and cured. An artificial crown 11 is added inside the matrixband 10 and formed to the anatomical shape of a crown. After thematerial of the crown 11 has been cured, it is attached to the matrixband 10 that supports the crown-root-system. A layer of a restorativecomposite resin 12 is then placed over the matrix band 10 to offer apolishable surface for the finished crown.

FIG. 4 illustrates schematically the use of a matrix band according to afourth embodiment of the invention, in endodontic treatment to protectthe root canal from saliva contamination during the treatment. Apremolar 13 needing endodontic treatment is firstly restored by a matrixband according to the present invention, thus forming a funnel 14 thatprevents the saliva from entering the root canal 15. The thus formedfunnel 14 allows aseptic endodontic treatment to be performed in amanner known per se, with endodontic instruments 16.

FIG. 5 illustrates schematically a device for the positioning of amatrix band according to the invention. The matrix band 17 is arrangedto a device 18 that allows the easy positioning of said matrix band 17on the tooth 19.

FIG. 6 illustrates schematically the use of a matrix band according to afifth embodiment of the invention. More specifically, the Figureillustrates a matrix band 20 according to the present invention in themanufacturing of a mesial filling of a molar tooth 21. In thisembodiment, the matrix band 20 is used as a partial covering in therestoration of a decayed molar tooth 21 needing a mesial filling 22. Thematrix band 20 is placed on the tooth and cured. When the fillingmaterial is cured, it attaches to the matrix band 20 thus forming afilling-matrix band-system that supports the tooth against newfractures.

Experimental Part

The matrix band according to the present invention was tested in adental restoration. The resulting restoration was tested against cuspfracture and compared to the cusp fracture of a restoration made in aconventional manner.

A buccal cusp of a premolar tooth was drilled away and restorated withZ250 restorative composite resin (3M Espe). One restoration wasmanufactured without a matrix band according to the present invention(A) and one restoration was manufactured with a matrix band according tothe present invention (B).

The repaired cusps were then loaded in 45° with a material testingmachine (Model LRX, Lloyd Instruments) and the results are shown in FIG.7. It can be seen that the tooth having a matrix band according to thepresent invention (B) was approximately 30% stronger that the toothwithout said matrix band (A).

1. A matrix band, consisting essentially of fibers and a matrix, atleast a portion of said matrix being at least partially uncured. 2.Matrix band according to claim 1, wherein a portion of said matrix is ina cured form.
 3. Matrix band according to claim 1 wherein said matrix isselected from the group consisting of methyl methacrylate, hydroxyethylmethacrylate, urethan dimethacrylate, triethylene glycol dimethacrylate,2,2-bis(4-(2-hydroxy-3-methacryloxy)phenyl)propane, polymethylmethacrylate, starburst methacrylated polyesters, hyperbranchedmethacrylated polyesters and mixtures thereof.
 4. Matrix band accordingto claim 1, wherein said fibers are selected from the group consistingof inert glass fibers, bioactive glass fibers, silica fibers, quartzfibers, ceramic fibers, carbon/graphite fibers, aramid fibers, ceramicfibers, poly(p-phenylene-2,6-benzobisoxazole) fibers,poly(2,6-diimidazo(4,5-b4′,5′-e)pyridinylene-1,4(2,5-dihydro)phenylenefibers, polyolefin fibers, fibers prepared from copolymers of olefins,polyester fibers, polyamide fibers, polyacrylic fibers, sol-gelprocessed silica fibers, collagen fibers, cellulose fibers, modifiedcellulose fibers and mixtures thereof.
 5. Matrix band according to claim1, wherein said fibers are in the form of continuous fibers, choppedfibers, mat, sheet or mixtures thereof, and wherein they are oriented inone, two, three or four directions, randomly or mixtures thereof. 6.Matrix band according to claim 1, wherein it further comprisesparticulate filler material.
 7. Matrix band according to claim 6,wherein said particulate filler material is selected from the groupconsisting of inert glass, bioactive glass, metal oxides, ceramics,polymers and mixtures thereof.
 8. A dental restoration kit comprising amatrix band according to claim 1, a restorative dental composite and anadhesive.
 9. Kit according to claim 8, wherein it further comprises anapplicator device.
 10. Kit according to claim 8, wherein said matrixband is preshaped in the form of a dental restoration, a dental crown ora dental bridge.
 11. A prepreg comprising fibers and a matrix, at leasta portion of said matrix being at least partially uncured, for use as adental matrix band.
 12. Use of a matrix band according to claim 1 forthe manufacturing of a dental restoration, a dental bridge or a dentalcrown.
 13. Use according to claim 12, wherein said matrix band forms anintegral part of the finished dental restoration, dental bridge ordental crown.
 14. Use of a matrix band according to claim 1 in dentalapplications.
 15. Use according to claim 14, wherein said application isselected from dental restoration, dental bridge, dental crown andendodontic treatment.